No arrests had been made. The shootings did not appear to be random, Techmeyer said.

Deputies were investigating a report that a man was seen with a rifle, but Techmeyer called that information "pretty sketchy."

The injured people were in a white sport-utility vehicle and drove themselves from Red Rocks to a Denver intersection about 15 miles away, but it was not clear why, Techmeyer said. They were eventually stopped by Denver police and taken to a hospital.

Investigators did not know if more people had been in the SUV before police stopped it, he said.

Techmeyer didn't know how many people were at the concert, but he said investigators stopped and questioned each car as it was leaving.

Traffic was chaotic and slow, but "we had a shooter out there," he said.

Witnesses were being interviewed until the early morning hours Friday.

The Red Rocks amphitheater and surrounding park are popular with joggers and sightseers. Most of the park had reopened Friday morning, but the area of the shooting remained sealed off.